Oscar we've talked about this elsewhere, but so if you go back to Menoeceus, Epicurus says that pleasure is our FIRST INNATE GOOD. Babies are born and no one has to teach them to shun pain and seek pleasure. So based on the study of nature, Epicurus said, we can see that THIS is what we are naturally drawn to doing. The key is that we should not force nature, but to work with her (PD 20). Epicurus is a very gentle teacher. He doesn't think you should work against your nature, he thinks you should be authentic.
Another way to think about this, if you don't like thinking of our ethics in terms of the goal, is to say that Pleasure is how we EXPERIENCE the good. Pain is how we EXPERIENCE evil. We are sentient beings, and a true and compassionate ethics concerns itself with the immediate, direct experience of sentient beings.